ThreadLocal 引起的内存泄露

最近在用LOADRUNNER做性能测试， 

运行几个小时后，内存一直增加， 最后出现了内存OutMemory问题。 

 

已知的一个BUG：

http://java.net/jira/browse/JAXB-844

 

 

JAXB 2.1.15 有问题类Coordinator 

 

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 * 
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 * 
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 * 
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
 * Sun designates this particular file as subject to the "Classpath" exception
 * as provided by Sun in the GPL Version 2 section of the License file that
 * accompanied this code.  If applicable, add the following below the License
 * Header, with the fields enclosed by brackets [] replaced by your own
 * identifying information: "Portions Copyrighted [year]
 * [name of copyright owner]"
 * 
 * Contributor(s):
 * 
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package com.sun.xml.bind.v2.runtime;

import java.util.HashMap;

import javax.xml.bind.ValidationEvent;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.bind.ValidationEventLocator;
import javax.xml.bind.annotation.adapters.XmlAdapter;
import javax.xml.bind.helpers.ValidationEventImpl;

import com.sun.xml.bind.v2.ClassFactory;
import com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext;

import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

/**
 * Object that coordinates the marshalling/unmarshalling.
 *
 * <p>
 * This class takes care of the logic that allows code to obtain
 * {@link UnmarshallingContext} and {@link XMLSerializer} instances
 * during the unmarshalling/marshalling.
 *
 * <p>
 * This is done by using a {@link ThreadLocal}. Therefore one unmarshalling/marshalling
 * episode has to be done from the beginning till end by the same thread.
 * (Note that the same {@link Coordinator} can be then used by a different thread
 * for an entirely different episode.)
 *
 * This class also maintains the user-configured instances of {@link XmlAdapter}s.
 *
 * <p>
 * This class implements {@link ErrorHandler} and propages erros to this object
 * as the {@link ValidationEventHandler}, which will be implemented in a derived class.
 *
 * @author Kohsuke Kawaguchi
 */
public abstract class Coordinator implements ErrorHandler, ValidationEventHandler {
    
    private final HashMap<Class<? extends XmlAdapter>,XmlAdapter> adapters =
            new HashMap<Class<? extends XmlAdapter>,XmlAdapter>();


    public final XmlAdapter putAdapter(Class<? extends XmlAdapter> c, XmlAdapter a) {
        if(a==null)
            return adapters.remove(c);
        else
            return adapters.put(c,a);
    }

    /**
     * Gets the instance of the adapter.
     *
     * @return
     *      always non-null.
     */
    public final <T extends XmlAdapter> T getAdapter(Class<T> key) {
        T v = key.cast(adapters.get(key));
        if(v==null) {
            v = ClassFactory.create(key);
            putAdapter(key,v);
        }
        return v;
    }

    public <T extends XmlAdapter> boolean containsAdapter(Class<T> type) {
        return adapters.containsKey(type);
    }

    /**
     * The {@link Coordinator} in charge before this {@link Coordinator}.
     */
    private Coordinator old;

    /**
     * A 'pointer' to a {@link Coordinator} that keeps track of the currently active {@link Coordinator}.
     * Having this improves the runtime performance.
     */
    private Coordinator[] table;

    /**
     * When we set {@link #table} to null, record who did it.
     * This is for trouble-shooting a possible concurrency issue reported at:
     * http://forums.java.net/jive/thread.jspa?threadID=15132
     */
    public Exception guyWhoSetTheTableToNull;

    /**
     * Associates this {@link Coordinator} with the current thread.
     * Should be called at the very beginning of the episode.
     */
    protected final void setThreadAffinity() {
        table = activeTable.get();
        assert table!=null;
    }

    /**
     * Dis-associate this {@link Coordinator} with the current thread.
     * Sohuld be called at the end of the episode to avoid memory leak.
     */
    protected final void resetThreadAffinity() {
        if(debugTableNPE)
            guyWhoSetTheTableToNull = new Exception(); // remember that we set it to null 
        table = null;
    }

    /**
     * Called whenever an execution flow enters the realm of this {@link Coordinator}.
     */
    protected final void pushCoordinator() {
        old = table[0];
        table[0] = this;
    }

    /**
     * Called whenever an execution flow exits the realm of this {@link Coordinator}.
     */
    protected final void popCoordinator() {
        assert table[0]==this;
        table[0] = old;
        old = null; // avoid memory leak
    }

    public static Coordinator _getInstance() {
        return activeTable.get()[0];
    }

    // this much is necessary to avoid calling get and set twice when we push.
    private static final ThreadLocal<Coordinator[]> activeTable = new ThreadLocal<Coordinator[]>() {
        public Coordinator[] initialValue() {
            return new Coordinator[1];
        }
    };


//
//
// ErrorHandler implementation
//
//
    /**
     * Gets the current location. Used for reporting the error source location.
     */
    protected abstract ValidationEventLocator getLocation();

    public final void error(SAXParseException exception) throws SAXException {
        propagateEvent( ValidationEvent.ERROR, exception );
    }

    public final void warning(SAXParseException exception) throws SAXException {
        propagateEvent( ValidationEvent.WARNING, exception );
    }

    public final void fatalError(SAXParseException exception) throws SAXException {
        propagateEvent( ValidationEvent.FATAL_ERROR, exception );
    }

    private void propagateEvent( int severity, SAXParseException saxException )
        throws SAXException {

        ValidationEventImpl ve =
            new ValidationEventImpl( severity, saxException.getMessage(), getLocation() );

        Exception e = saxException.getException();
        if( e != null ) {
            ve.setLinkedException( e );
        } else {
            ve.setLinkedException( saxException );
        }

        // call the client's event handler.  If it returns false, then bail-out
        // and terminate the unmarshal operation.
        boolean result = handleEvent( ve );
        if( ! result ) {
            // bail-out of the parse with a SAX exception, but convert it into
            // an UnmarshalException back in in the AbstractUnmarshaller
            throw saxException;
        }
    }

    public static boolean debugTableNPE;

    static {
        try {
            debugTableNPE = Boolean.getBoolean(Coordinator.class.getName()+".debugTableNPE");
        } catch (SecurityException t) {
        }
    }
}

 

 

变量adapters一直没有进行REMOVE操作 

 

JAXB（V2.2.25）修复后的代码如下：

 

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright (c) 1997-2011 Oracle and/or its affiliates. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License.  You can
 * obtain a copy of the License at
 * https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
 * or packager/legal/LICENSE.txt.  See the License for the specific
 * language governing permissions and limitations under the License.
 *
 * When distributing the software, include this License Header Notice in each
 * file and include the License file at packager/legal/LICENSE.txt.
 *
 * GPL Classpath Exception:
 * Oracle designates this particular file as subject to the "Classpath"
 * exception as provided by Oracle in the GPL Version 2 section of the License
 * file that accompanied this code.
 *
 * Modifications:
 * If applicable, add the following below the License Header, with the fields
 * enclosed by brackets [] replaced by your own identifying information:
 * "Portions Copyright [year] [name of copyright owner]"
 *
 * Contributor(s):
 * If you wish your version of this file to be governed by only the CDDL or
 * only the GPL Version 2, indicate your decision by adding "[Contributor]
 * elects to include this software in this distribution under the [CDDL or GPL
 * Version 2] license."  If you don't indicate a single choice of license, a
 * recipient has the option to distribute your version of this file under
 * either the CDDL, the GPL Version 2 or to extend the choice of license to
 * its licensees as provided above.  However, if you add GPL Version 2 code
 * and therefore, elected the GPL Version 2 license, then the option applies
 * only if the new code is made subject to such option by the copyright
 * holder.
 */

package com.sun.xml.bind.v2.runtime;

import java.util.HashMap;

import javax.xml.bind.ValidationEvent;
import javax.xml.bind.ValidationEventHandler;
import javax.xml.bind.ValidationEventLocator;
import javax.xml.bind.annotation.adapters.XmlAdapter;
import javax.xml.bind.helpers.ValidationEventImpl;

import com.sun.xml.bind.v2.ClassFactory;
import com.sun.xml.bind.v2.runtime.unmarshaller.UnmarshallingContext;

import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;

/**
 * Object that coordinates the marshalling/unmarshalling.
 *
 * <p>
 * This class takes care of the logic that allows code to obtain
 * {@link UnmarshallingContext} and {@link XMLSerializer} instances
 * during the unmarshalling/marshalling.
 *
 * <p>
 * This is done by using a {@link ThreadLocal}. Therefore one unmarshalling/marshalling
 * episode has to be done from the beginning till end by the same thread.
 * (Note that the same {@link Coordinator} can be then used by a different thread
 * for an entirely different episode.)
 *
 * This class also maintains the user-configured instances of {@link XmlAdapter}s.
 *
 * <p>
 * This class implements {@link ErrorHandler} and propages erros to this object
 * as the {@link ValidationEventHandler}, which will be implemented in a derived class.
 *
 * @author Kohsuke Kawaguchi
 */
public abstract class Coordinator implements ErrorHandler, ValidationEventHandler {
    
    private final HashMap<Class<? extends XmlAdapter>,XmlAdapter> adapters =
            new HashMap<Class<? extends XmlAdapter>,XmlAdapter>();


    public final XmlAdapter putAdapter(Class<? extends XmlAdapter> c, XmlAdapter a) {
        if(a==null)
            return adapters.remove(c);
        else
            return adapters.put(c,a);
    }

    /**
     * Gets the instance of the adapter.
     *
     * @return
     *      always non-null.
     */
    public final <T extends XmlAdapter> T getAdapter(Class<T> key) {
        T v = key.cast(adapters.get(key));
        if(v==null) {
            v = ClassFactory.create(key);
            putAdapter(key,v);
        }
        return v;
    }

    public <T extends XmlAdapter> boolean containsAdapter(Class<T> type) {
        return adapters.containsKey(type);
    }

    /**
     * The {@link Coordinator} in charge before this {@link Coordinator}.
     */
    private Object old;

    /**
     * A 'pointer' to a {@link Coordinator} that keeps track of the currently active {@link Coordinator}.
     * Having this improves the runtime performance.
     */
    private Object[] table;

    /**
     * When we set {@link #table} to null, record who did it.
     * This is for trouble-shooting a possible concurrency issue reported at:
     * http://forums.java.net/jive/thread.jspa?threadID=15132
     */
    public Exception guyWhoSetTheTableToNull;

    /**
     * Associates this {@link Coordinator} with the current thread.
     * Should be called at the very beginning of the episode.
     */
    protected final void setThreadAffinity() {
        table = activeTable.get();
        assert table!=null;
    }

    /**
     * Dis-associate this {@link Coordinator} with the current thread.
     * Sohuld be called at the end of the episode to avoid memory leak.
     */
    protected final void resetThreadAffinity() {
        if (activeTable != null) {
            activeTable.remove();
        }
        if(debugTableNPE)
            guyWhoSetTheTableToNull = new Exception(); // remember that we set it to null 
        table = null;
    }

    /**
     * Called whenever an execution flow enters the realm of this {@link Coordinator}.
     */
    protected final void pushCoordinator() {
        old = table[0];
        table[0] = this;
    }

    /**
     * Called whenever an execution flow exits the realm of this {@link Coordinator}.
     */
    protected final void popCoordinator() {
        assert table[0]==this;
        table[0] = old;
        old = null; // avoid memory leak
    }

    public static Coordinator _getInstance() {
        return (Coordinator) activeTable.get()[0];
    }

    // this much is necessary to avoid calling get and set twice when we push.
    private static final ThreadLocal<Object[]> activeTable = new ThreadLocal<Object[]>() {
        @Override
        public Object[] initialValue() {
            return new Object[1];
        }
    };

//
//
// ErrorHandler implementation
//
//
    /**
     * Gets the current location. Used for reporting the error source location.
     */
    protected abstract ValidationEventLocator getLocation();

    public final void error(SAXParseException exception) throws SAXException {
        propagateEvent( ValidationEvent.ERROR, exception );
    }

    public final void warning(SAXParseException exception) throws SAXException {
        propagateEvent( ValidationEvent.WARNING, exception );
    }

    public final void fatalError(SAXParseException exception) throws SAXException {
        propagateEvent( ValidationEvent.FATAL_ERROR, exception );
    }

    private void propagateEvent( int severity, SAXParseException saxException )
        throws SAXException {

        ValidationEventImpl ve =
            new ValidationEventImpl( severity, saxException.getMessage(), getLocation() );

        Exception e = saxException.getException();
        if( e != null ) {
            ve.setLinkedException( e );
        } else {
            ve.setLinkedException( saxException );
        }

        // call the client's event handler.  If it returns false, then bail-out
        // and terminate the unmarshal operation.
        boolean result = handleEvent( ve );
        if( ! result ) {
            // bail-out of the parse with a SAX exception, but convert it into
            // an UnmarshalException back in in the AbstractUnmarshaller
            throw saxException;
        }
    }

    public static boolean debugTableNPE;

    static {
        try {
            debugTableNPE = Boolean.getBoolean(Coordinator.class.getName()+".debugTableNPE");
        } catch (SecurityException t) {
        }
    }
}

 

 

主要是加了下面这个代码修复了内存泄露问题

 

 

    /**
     * Dis-associate this {@link Coordinator} with the current thread.
     * Sohuld be called at the end of the episode to avoid memory leak.
     */
    protected final void resetThreadAffinity() {
        if (activeTable != null) {
            activeTable.remove();
        }
        if(debugTableNPE)
            guyWhoSetTheTableToNull = new Exception(); // remember that we set it to null 
        table = null;
    }

 

所以由THREADLOCAL创建的变量一定要进行REMOVE操作

 

原文：http://extjs2.iteye.com/admin/blogs/1701172

评论

4 楼 xiaoguang0904 2013-03-26  

eimhee 写道

xiaoguang0904 写道

最新的jaxb里面这个方法也没有改！

最新的JAXB已经没这个问题吧

最新的的确没这个问题了。

3 楼 eimhee 2013-03-12  

xiaoguang0904 写道

最新的jaxb里面这个方法也没有改！

最新的JAXB已经没这个问题吧

2 楼 xiaoguang0904 2013-03-11  

最新的jaxb里面这个方法也没有改！

1 楼 xiaoguang0904 2013-03-11  

jaxb 有 2.2.25吗？